1. Field of the Invention
The present invention pertains to an apparatus and method for attaching an object to bone and, in particular, to a fixation device and method for using the fixation device, wherein the device is rotated within an elongated channel formed in a bone such that a portion of the fixation device lies under the bone and objects are attached to the bone using the thus implanted fixation device.
2. Description of the Related Art
A wide variety of devices and methods are known for attaching an object to bone. One such device is disclosed in U.S. Pat. No. 5,041,129, wherein a cylindrical-shaped suture anchor is ejected, end-first, from an insertion tool into a bore formed in a bone. The ends of the suture anchor are beveled and engage the walls of the bore thereby lodging the suture anchor within the bore. The cylindrical-shaped suture anchor has a single suture internally attached to an end of the suture anchor such that the suture extends through a hollow center of the suture anchor. The suture exits from the hollow center at the mid-section of the suture anchor through a channel that extends along the surface of the suture anchor. The suture is used to attach objects to the bone.
This device for affixing an object to bone, however, does not always result in a secure placement of the suture anchor within the bone. The positioning of the suture anchor within the bore is random and depends on such factors as the density of the bone tissue and the presence of bone cavities near the bore. There is no way to precisely control where the cylindrical-shaped suture anchor will engage the walls of the bore after it is ejected from the insertion tool. In addition, if the suture anchor is inserted into a bone comprised mostly of soft tissue, the sharply beveled ends of the suture anchor are likely to cut through the soft tissue when a force is applied to the suture, possibly pulling the anchor out of the bone. Therefore, this device for attaching an object to bone is not suitable for all bone types.
In addition, the suture anchor taught by this patent includes only one suture extending from the mid-section thereof. Because at least two sutures are necessary to tie a ligature, at least two such suture anchors must be implanted into the bone to accomplish this object. Obviously, it is desirable to use as few suture anchors as possible to minimize damage to the patient's tissues.
U.S. Pat. No. 5,203,782 discloses another device for attaching an object to bone. According to this patent, the suture anchor has a spring-shaped elongated body with relatively long legs extending therefrom. The suture anchor is positioned within a bore formed in the bone such that each leg extends in opposite directions parallel to the length of the bore. A suture is attached to the mid-section of the suture anchor such that the suture anchor rotates within the bore when a force is applied to the suture. The legs have sharpened ends that engage the walls of the bore during this rotation. As with the previously described suture anchor device, the positioning of the suture anchor cannot be precisely controlled. The rotation of the suture anchor is random depending on the cavities and softness or density of the bone tissue near the bore. Furthermore, the sharp ends of the legs cut into the soft bone tissue. Therefore, this suture anchor is also not suitable for all types of bones.